By way of background, it is noted that the term "pressure system" as used herein generally refers, for instance, to a cooling circuit comprising a cooling device, a collector of a liquid cooling medium of a cooling circuit as well as to any vessel for a low boiling medium, e.g., a transport vessel for a liquid cooling medium, a storage vessel of a low boiling medium for filling of fire extinguishers and the like. Further, the expression "low boiling liquid" or "low boiling media" generally refers to, for example, fluorinated and chlorinated hydrocarbons used, e.g., as cooling agents and identified by the name Freon, as well as to halogenated hydrocarbons used for fire extinguishers, liquefied gasses and all other liquids having a low boiling point lower than 80.degree. C. at normal barometric pressure.
In different industrial branches, businesses and services, health services, agriculture and households, systems and arrangements are used which employ, as a working agent, a low boiling medium contained within a pressure system. In many instances, these workings agents are objectionable, i.e., present problems, for reasons of health and hygiene, and sometimes for ecological reasons as well. Such media characteristically have to be drawn off on a frequent bases from the pressure systems. These media are in many cases discharged into the atmosphere; alternatively, specially designed pumping devices are used and in such instances, residual vapors of the cooling agent, which remain after pumping off of the liquid, cannot be easily removed. For instance, in cases where for some reason the cooling agent from condensation cooling units and cooling circuits must be removed or pumped off, vapors of the cooling agent are generally discharged into the surrounding atmosphere. It is a widely accepted fact that fluorinated and chlorinated hydrocarbons used as cooling agents affect the protective ozone layer of the atmosphere thereby significantly influencing the global environmental conditions. Accordingly, much worldwide attention has been focused on how to prevent the leakage of such cooling agents into the atmosphere.
In presently known arrangements provided for drawing off of cooling agents, such as described, for instance, in German Federal Republic Patent No. 3,001,224, (based on U.S. application), the problem of drawing off vapors of cooling agents from cooling circuits and condensation units has been addressed. However, because of the nature of the pumping provided and the undercooling provided by the cooling unit, and due to distillation of the cooling agent, a substantial part of contaminants contained in the liquid cooling agent remain in the circuit. This is particularly true of products ranging from built-in electric motors which are damaged due to short circuits, to semi-hermetic and hermetic compressors, contaminated oil and other contaminants which, under prevailing conditions, have a boiling temperature higher than that of the cooling agent used. Because practically the entire amount of cooling agent is pumped off by way of a suction filter and a compressor which is generally of a hermetic design, the life-time of the compressor is reduced, the consumption of electric power is increased and the suction filter is required to be changed frequently. Further, prior art arrangements of this kind have usually an overall weight around 50 kg, and are costly. Further, handling of these arrangements or units is difficult and physically demanding.